The solubility of the woolen fibers in potash lye is a ready means of ascertaining the percentage of wool fiber in the paper. An exhaustive analysis of the latter can be performed in the following manner: A known quantity of the paper is slowly dried in a drying apparatus at temperature of 230° Fahrenheit, until a sample weighed on a scale remains constant. The loss of weight indicates the degree of humidity. To determine the ash percentage, the sample is placed in a platinum crucible, and held over a lamp until all the organic matter is burned out and the ash has assumed a light color. The cold ash is then moistened with a carbonate of ammonia solution, and the crucible again exposed until it is dark red; the weight of the ash is then taken. To determine the percentage of wool, a sample of the paper is dried at 230° Fahrenheit and weighed, boiled in a porcelain dish in potash lye 12° B. strong, and frequently stirred with a glass rod. The wool fiber soon dissolves in the potash lye, while the vegetable fiber remains unaltered. The pulpy mass resulting is placed upon a filter, dried at 212° Fahrenheit, and after the potash lye has dripped off, the residue, consisting of vegetable fiber and earthy ash ingredients, is washed until the water ceases to dissolve anything. The residue dried at 212° Fahrenheit is weighed with a filter, after which that of the latter is deducted. The loss of weight experienced is essentially equal to the loss of the wool fiber. If the filtrate is saturated with hydrochloric acid, the dissolved wool fiber separates again, and after having been collected upon a weighed filter, it may be weighed and the quantity ascertained. The weight of the mineral substances in the raw paper is ascertained by analyzing the ash in a manner similar to that above described. The several constituents of the ash and the mineral added to the raw paper are ascertained as follows: Sufficient of the paper is calcined in the manner described; a known quantity of the ash is weighed and thrown into a small porcelain dish containing a little distilled water and an excess of chemically pure hydrochloric acid. In this solution are dissolved the carbonates, carbonate of lime, carbonate of magnesia, a little of sulphate of alumina, as well as metallic oxides, while silicate of magnesia, silicic acid, sulphate of lime (gypsum) remain undissolved. The substance is heated until the water and excess of free hydrochloric acid have been driven off; it is then moistened with a little hydrochloric acid, diluted with distilled water and heated. The undissolved residue is by filtering separated from the dissolved, the filter washed with distilled water, and the wash water added to the filtrate. The undissolved residue is dried, and after the filter has also been burned in due manner and the ash added, the weight is ascertained. It consists of clay, sand, silicic acid and gypsum.